In the article [S. Lo et al., “Signal Authentication: A Secure Civil GNSS for Today”, Inside GNSS September/October 2009] a position and time authentication based on the military GPS (GPS=global positioning system) signals is described. According to the proposed concept, the raw data including the military GPS signals have to be recorded constantly nearby the position of interest, to be able to prove the position and time later on by a cross-correlation between the snapshot signal and its reference received counterpart.
Moreover, a proof-of-concept to extract position and time out of a GPS-snapshot is given in the article [Wu, J.; Dempster, A.; “Data Compression of Assisted-GPS Signal Processing”, Proceedings of the 24th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS 2011)].
In addition, in the article [Kelsey, J.; Schneier, B.; Hall, C.; “An authenticated camera,” Computer Security Applications Conference, 1996., 12th Annual, vol., no., pp. 24-30, 9-13 Dec. 1996; doi: 10.1109/CSAC.1996.569666;] an approach for an “authenticated camera” using a certain interaction between the camera and its base station before and after its usage is presented. However, the biggest gap identified in the proposed architecture is the strong need for authenticated location data.